The reboots are most likely caused by the watchdog not being triggered, that is a concern that needs to be tackled - but you should still (first) get grub2 going (yes, even then it will reboot after a few seconds, but seeing the grub2 menu would still be a first partial success).
Maybe your system needs UEFI64, maybe it needs UEFI32, maybe it needs BIOS booting - we don't know at this point (and it's way harder to find out without being able to observe the OEM firmware), but determining this topic of getting grub2 (or any bootloader) working may be easier to debug with a general purpose Linux distribution (e.g. Debian), as OpenWrt's UEFI support is rather new and not as well established and battle tested than that of more common desktop-/ server distributions.
i can't do this, because i can't stop the process, all i can do is hit the F12 key when i'm asked.
i tried to boot from a Debian LiveCD, it didn't work. i just tried now with a debian netinstall, same.
this is the output when i choose the usb key after F12.
Build date: Apr 26 2018
(re)init TCO watchdog
Press F12 for boot menu.
Select boot device:
1. USB MSC Drive Kingston DataTraveler 120 PMAP
2. USB MSC Drive Generic Ultra HS-COMBO 1.98
Searching bootorder for: HALT
Mapping hd drive 0x000f2a10 to 0
drive 0x000f2a10: PCHS=0/0/0 translation=lba LCHS=1024/255/63 s=31375360
Mapping hd drive 0x000f29e0 to 1
drive 0x000f29e0: PCHS=0/0/0 translation=lba LCHS=950/255/63 s=15269888
finalize PMM
malloc finalize
Space available for UMB: c4000-f0000, f0000-f29e0
Returned 249856 bytes of ZoneHigh
e820 map has 8 items:
0: 0000000000000000 - 000000000009e800 = 1 RAM
1: 000000000009e800 - 00000000000a0000 = 2 RESERVED
2: 00000000000f0000 - 0000000000100000 = 2 RESERVED
3: 0000000000100000 - 000000007fbdd000 = 1 RAM
4: 000000007fbdd000 - 000000007fe00000 = 2 RESERVED
5: 00000000e0000000 - 00000000f0000000 = 2 RESERVED
6: 00000000fee00000 - 00000000fee01000 = 2 RESERVED
7: 0000000100000000 - 0000000180000000 = 1 RAM
Jump to int19
enter handle_19:
NULL
Booting from Hard Disk...
Booting from 0000:7c00
enter handle_12:
a=00000000 b=00000000 c=00000000 d=00000000 ds=0000 es=0000 ss=9000
si=00000000 di=00000000 bp=00000000 sp=0000fff0 cs=0000 ip=8c2f f=0000
enter handle_12:
a=00000200 b=00000000 c=00000000 d=00000000 ds=0000 es=0000 ss=9000
si=00000000 di=00000000 bp=00000000 sp=0000fff0 cs=0000 ip=8c2f f=0000
but does the cable have a serial port/UART embedded, as an active component ?
or do I simply hook up the cable to a PC, and it will detect the Velocloud as a serial port ?
i don't know how they boot from usb with all their distros, it doesn't work for me...so i can't take control of the shell to write a single command...
i'm wondering if my usbkeys are correctly burned with Rufus....
The serial worked for me, just the way you described it, thnx! - 115200, N81.
But the 500 runs AMI BIOS, and I'm able to stop the boot process, and get the GRUB boot menu.
Processor Type: Intel(R) Atom(TM) CPU C2358 @ 1.74GHz
Processor Speed: 1743 MHz
Total Memory: 4096MB (DDR3 1333)
USB Devices total: 0 KBDs, 0 MICE, 0 MASS, 1 HUBs
Detected ATA/ATAPI Devices...
Version 2.16.1242. Copyright (C) 2013 American Megatrends, Inc.
CASwell, Inc. COB-G800-000 Rev.:R1.00 ( 20141209 )
Press <DEL> or <TAB> to enter setup.
Press <B> to enter BBS POPUP.